The present invention relates generally to printing presses and more specifically to a printing unit with a roll-away inking unit.
U.S. Pat. No. 5,025,726 discloses a movable inker type printing machine in which an inker for a satellite printing press is automatically detachable to the press when in a clutch-off position, and automatically connects itself to the press when a clutch-on instruction is received. The plate cylinders of the printing press are plated in a conventional manner.
U.S. Pat. No. 5,640,906 discloses a short multi-color web-fed rotary printing press utilizing a vertical stack of bridge printing units which are supported by horizontally shiftable frame sections. Inking units move with their respective printing cylinders on a common frame.
An object of the present invention is to provide a printing unit in which the plate cylinder can be easily imaged with a minimum of space requirements. Another alternate or additional object of the present invention is to provide for easy imaging of a vertical stack printing unit.
The present invention thus provides a printing unit having a plate cylinder, a blanket cylinder for printing a first side of a web of material, and an inker for inking the plate cylinder, the inker being movable between an active position and an inactive position, the inker contacting the plate cylinder in the active position and the inker being separated from the plate cylinder in the inactive position. A plate operation unit is movable into the active position of the inker when the inker is in the inactive position.
The plate operation unit, which may be for example an imaging device or an automatic plate exchanger, may then perform an operation on the plate cylinder while the inker is in the inactive position. When in use in a vertical stack or other configuration, the amount of space about the plate cylinder for inking and plating can be reduced, as the same area on the plate cylinder is used for both functions.
xe2x80x9cPlate cylinderxe2x80x9d as defined herein includes any imaging unit, and may include plate cylinders with attachable flat or sleeve-shaped plates, and may also include directly imagable cylinders. When the plate cylinder is used with flat plates, the plate operation unit preferably is an automatic plating mechanism, and when the plate cylinder is directly imagable, the plate operation unit preferable is an imaging device, which may include for example a laser for imaging the plate cylinder.
The inker preferably includes a plurality of inker rolls, and may be moved on a carriage in a manner similar to that disclosed in U.S. Pat. No. 5,025,726, which is hereby incorporated be reference herein.
The plate cylinder and blanket cylinder preferably are mounted rotatably to a center frame section, and the inker is mounted to a first frame section movable with respect to the center frame section.
Preferably, the printing unit further includes a second plate cylinder, a second blanket cylinder for printing a second side of the web, a second inker for inking the second plate cylinder, the second inker being movable between a second active position and a second inactive position, the second inker contacting the second plate cylinder in the second active position and the second inker being separated from the second plate cylinder in the second inactive position. A second plate operation unit is movable into the second active position of the second inker when the second inker is in the second inactive position.
The plate cylinder, blanket cylinder, second plate cylinder and second blanket cylinder all may be supported rotatably on a center frame section, and the second inker may be supported on a second frame section movable with respect to the center frame section.
Preferably, the inker has inker rollers, at least one of which contacts the plate cylinder when the inker is in the active position. The second inker also preferably has second inker rollers at least one of which contacts the second plate cylinder when the second inker is in the active position.
A dampening unit for the plate cylinder may be connected to the center frame section, as may be a second dampening unit for the second plate cylinder may also be connected to the center frame. Alternately, the dampening units may be connected to the movable first or second frame sections and thus be considered to define part of the respective active position together with their respective inking units.
An overhead hoist may be provided to assist in the removal of cylinders or rollers.
Preferably, the plate cylinder and the second plate cylinder are in a similar horizontal plane.
The plate cylinder and the blanket cylinder may be driven by a common drive motor or by two individual drive motors. Further, the blanket cylinder and the second blanket cylinder may be driven by a common drive motor and each of the plate cylinder and the second plate cylinder by an individual drive motor. The motors may be driven by one of the drive motors of the plate cylinders or the blanket cylinders. It is also possible to drive the inkers by at least one individual drive motor.
Preferably, a roll-away mechanism for the movable side frame, I.e. the first frame section and the second frame section, is provided, e.g. a motor-driven mechanism with a rail system supporting the movable sections. Moreover, a linear motor can be used to roll away the movable sections.
The blanket cylinder may act with the second blanket cylinder to print the web from both sides or may with an impression cylinder to print the web from only one side.
The present invention also provides a method for performing an operation on a plate cylinder comprising the steps of:
inking the plate cylinder with an inking unit at a first circumferential location of the plate cylinder;
moving the inking unit out of contact with the plate cylinder; and
moving a plate operation unit to operate on the plate cylinder at the first circumferential location.